In an inkjet printing system of a piezo system, ink filled in an ink chamber is pushed out due to deformation of a piezoelectric element applied with a voltage so that ink is discharged from a nozzle.
Now, in the inkjet printing apparatus, since printing is performed to form an image, of course, printing is not performed to a portion where an image is absent.
Therefore, such an event occurs that even if a nozzle by which printing is not performed is in operation of the inkjet printing apparatus, ink on a nozzle surface (particularly, a meniscus portion) gradually evaporates and the ink dries so that solid content in the ink precipitates to adhere to an opening portion of the nozzle.
As a result, when the nozzle is used, there is a possibility of causing such a discharge defect that the ink cannot be discharged straightly due to clogging in the nozzle or a partial clogging therein.
On the other hand, an image-forming apparatus provided with a pressure application portion which performs a discharge action for discharging an ink drop from a nozzle and a swinging action which swings a meniscus of ink but does not discharge an ink drop is known (for example, see PTL1).
According to such an image-forming apparatus, prior to performing printing on a certain page, by swinging a meniscus of a nozzle corresponding to a printed pixel and maintaining a meniscus of a nozzle corresponding to a pixel which is not printed in a resting state, a discharge defect is hard to occur when printing is performed on the next page using a nozzle which did not discharge in printing the previous page.